您正在使用哪种框架，我很确定在某一时刻某些东西会将您数组转换为字符串，也许是对POST变量进行如下处理:

Which kind of framework are you using, I'm quite sure there is something at one point that is casting you're array into a string, maybe something that apply a treatment on POST variable like this:

foreach ($_POST as $key => $value) {
    if ($value && !$is_magic_quotes_gpc) {
        $_POST["$key"] = addslashes($value);
    }

在这种情况下，您必须删除此功能...要确定我在说什么，可以尝试var_dump($ POST [MyTextarea])=>字符串'Array'(length = 5)(应该是数组)

In this case you've to remove this function... To be sure of what I'm talking about, you can try a var_dump($POST[MyTextarea]) =>string 'Array' (length=5) (should be an array)